Question 1320
y=-5x^2 is easy!
You need to set "y" to zero (0)and you also need to know that you're adding zeros(0) to it: 
0=-5x^2+0+0
Now you do the quadratic formula:
{{{x=(-b+-sqrt(b^2-4*a*c))/(2*a)}}}

Then substitue by pluging in numbers with the letters(ax^2+bx+c)

And simplify:
{{{x=-0+-sqrt(0))/(-10)}}}

And this is your answer. Some answers are usually radicals.